Come to Daddy—after an elderly lady lets her dog take a leak on a TV, she is harassed by children, each one of their faces replaced by the identical grinning visage of Richard D. James, whilst a distorted face on the TV howls about how he wants your soul. It gets worse from then on in.
Once described by Dave Grohl as "the most terrifying music video ever."
The song itself is scary. Let's put it like this: it made My Neighbor Totoro scary. (Sadly, no YouTube link since the US has a copyright block on the video.)
"Gwarek2" off of Drukqs is highly unsettling, and was used in the above video.
Run "Equation" through a spectogram. Sweet Dreams....
The aforementioned hideously ugly woman from Chris Cunningham's music video of Windowlicker. Her face is actually based on a sketch by H. R. Giger, which, you guessed it, is called The Windowlickers.